Hmm...This is a hard one since I have seen a lot of scary movies.
Saw 1 and 2 - Hmm, not really scary but there are some scenes that will make you jump...But I don't see how any one of these two films could be my favourite scary movie, what's the point in making them a favourite if they're barely scary and get boring.
The Village - I don't think this is even supposed to be a scary movie, but some parts of it did scare me. Still, it's kinda difficult to make this my favourite.
It - ...I hate clowns and the idea of a killer clown seems a little...Over-Used, this wasn't scary :] Definately not my favourite (the clown was a big thumbs down, and a bit boring for a person who doesn't like clowns and movies that are cliché)
Friday The 13th (2009 Version) - Okay this has automatically succeeded in becoming my favourite scary movie...It scared me.
When a Stranger Calls - Darn this one scared the heck out of me...I got a phone call during the movie and nearly jumped out of my skin...Turns out my joker of a friend was also watching the movie and decided he would call and scare me.
So I have come to the decision "Friday the 13th (2009 Version)" is my favourite scary movie. Gotta love a movie that scares the poop out of you :]
"When a Stranger Calls" Has recieved second place for me

but it was so very close to becoming first.